Refer to the exhibit. Users at the branch office on R1 reported issues with an application at the home office on R4. While troubleshooting the issue, a network engineer determined that: - The…

Question

Exhibit

Options

• ARedistribute static connected routes in IS-IS on router RI.
• BConfigure the IS-IS core instance on the R1 GigabitEthernet0/3 interface.
• CRedistribute static connected routes in IS-IS on router R4.
• DConfigure the IS-IS core instance on the R2 GigabitEthernet0/1 interface.

• A
  14% (3)
• B
  71% (15)
• C
  5% (1)
• D
  10% (2)

Explanation

This question involves IS-IS multi-instance or multi-topology deployments where IS-IS is segmented by role (e.g., a 'core' instance and a 'branch' instance). The key clue is that R3 cannot reach the R1 172.16.10.0/24 network (the branch-side subnet), even though IS-IS adjacencies are up and traffic to R2's 10.20.1.0/24 network is working. This indicates that R1's GigabitEthernet0/3 interface (the interface facing the branch office) is participating only in the branch IS-IS instance but not in the core IS-IS instance. Because the branch-side network is not advertised into the core IS-IS instance, R3 and R4 have no visibility of 172.16.10.0/24. Configuring the IS-IS core instance on R1's GigabitEthernet0/3 interface causes R1 to advertise the branch subnet into the core topology, restoring reachability. Option A is wrong because IS-IS advertises connected and static routes natively when the interface is enabled under the process; redistribution is not typically needed. Option C redistributing on R4 would not help R3 learn R1's branch network. Option D configuring IS-IS on R2's interface would not resolve R1's missing advertisement.

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